Russian Defense Minister Sergei Shoigu said the mission by Russia's only aircraft carrier, the Admiral Kuznetsov, to the eastern Mediterranean was a success despite the loss of two fighter jets. He said the experience would help avoid "mistakes" in the future.

Shoigu has expressed satisfaction with Moscow's military campaign in Syria and says it has been a good test of new weapons and special-forces units.

In a speech to the lower house of parliament on February 22, Shoigu said that 162 new Russian weapons systems had been tested in Syria and that "only 10" failed to perform up to expectations.

Shoigu told the State Duma that 1,760 combat missions had been flown in Syria since Russia launched a campaign of air strikes in support of President Bashar al-Assad's government in September 2015.

He said that "nearly 90 percent" of Russia's military pilots had gained combat experience in Syria.

Western governments have criticized the Russian air campaign, saying that it has largely targeted rebels rather than Islamic State (IS) militants and has caused substantial civilian casualties.

Russia has given Assad's government crucial military and diplomatic support throughout the six-year war in Syria, which has killed some 300,000 people and driven many more from their homes.

The Russian air campaign has helped turn the tide of the conflict in favor of Assad, whose forces were under severe pressure and losing ground at the time.

Shoigu also said the mission by Russia's only aircraft carrier, the Admiral Kuznetsov, to the eastern Mediterranean was a success despite the loss of two fighter jets. He said the experience would help avoid "mistakes" in the future.

He said Russia's special forces "have demonstrated their considerable efficiency" in the conflict and "played a key role in liquidating terrorists, destroying important enemy facilities, and directing air strikes."

The exact number of Russian troops in Syria has not been made public, but experts put the figure at around 4,000.

Shoigu did not discuss casualties in Syria, which represents Moscow's biggest military campaign abroad since the Soviet war in Afghanistan in 1979-88.

Asked by lawmakers about "information warfare" and "counterpropaganda," Shoigu said that "information-operations troops have been set up."

"Propaganda should be smart, intelligent, and efficient," he told the Duma.

The Russian campaign in Syria, where the United States leads a coalition conducting air strikes targeting IS extremists, has added to tensions with the West following Moscow's seizure of Crimea in 2014 and support for separatists fighting Ukrainian government forces in eastern Ukraine.

Western governments say Russia is also using propaganda, cyberattacks, and other methods to interfere in politics and increase its influence abroad.

U.S. intelligence agencies said in January that they have concluded that Russia used hacking, leaks, and other methods to interfere in the U.S. presidential election in November.